Biology subjects

Brathen, K. A.

Publications and source records attributed to Brathen, K. A..

9 recordsLinked to original sources

bioRxiv2026

Testing people's aesthetic appreciation for biodiverse vegetation: Messiness is not a problem

O_LIBiodiverse vegetation that supports high rates of ecosystem functions can inherently express a messy appearance due to high numbers of local native plant species and their spatial distribution connected to niche complementarity. This messiness is assumed to lower peoples appreciation for vegetation in urban contexts. Since such vegetation and a positive relationship between people and biodiversity could contribute to mitigating biodiversity loss, this assumed low public appreciation warrants investigation. C_LIO_LIWe designed and constructed biodiverse flowerbeds using only local native plants, and with the intention to enhance planting productivity, resistance and resilience. To investigate the influence of messiness, we created flowerbeds in four high levels of species richness (8,12,16,20) shown to be relevant for ecosystem functioning, and three levels of order (no, semi, full). We tested public appreciation for the flowerbeds using a self-guided, on-site survey. C_LIO_LIWe found a positive mean rating for all flowerbeds, but no effect of species richness on the ratings. Increased order, however, had a strong negative effect: The odds of a fully ordered flowerbed receiving a negative rating were 88% higher than of a flowerbed with no order. Increasing designed order was correlated with decreasing plant biomass in the flowerbeds. C_LIO_LIThese findings challenge the assumption that the appearance of biodiverse plantings is too messy for public appreciation in urban contexts. Specifically, we demonstrate that introducing order and reducing messiness can compromise aesthetic appreciation for biodiverse vegetation, potentially by compromising productivity as indicated by lower biomass production in ordered plantings. C_LI Synthesis and applicationOur study shows that biodiverse vegetation can be appreciated in urban contexts. Flowerbeds can effectively serve both people as ornamentation and biodiversity as habitat when they are designed based on ecological principles Research highlightsO_LIWe designed and realized flowerbeds based on ecological principles. C_LIO_LIAll plantings received positive average ratings. C_LIO_LIIncreasing species richness in the flowerbeds did not affect participants aesthetic appreciation. C_LIO_LIIncreasing order in the design of the flowerbeds strongly lowered participants aesthetic appreciation. C_LIO_LIIncreasing order in the design was correlated to lower biomass productivity and more bare soil in the flowerbeds. C_LI

ecology↗

bioRxiv2024

Long-term homogenization of vascular plant and lichen communities across Fennoscandian heathlands and tundra is connected to the expansion of an allelopathic dwarf shrub

Boreal and tundra plant communities are expected to change in biodiversity due to increasing global change pressures such as climate warming. One long-term scenario is increasing compositional similarity, i.e., biotic homogenization, which has been relatively little studied in high-latitude plant communities. Here, we study how the composition and diversity of heathland and tundra plant communities have changed in northern Fennoscandia over several decades. In 2013-2023, we resurveyed 275 historic vegetation plots, originally surveyed in 1964-1975, with percentage covers for vascular plant, bryophyte and lichen species. We analyzed temporal changes in community composition and diversity across the study area and in different habitat types, biogeographic zones, and along the continentality-humidity gradient. We found a strong trend across the study area, with plant communities becoming more similar in composition over the decades. The observed homogenization was associated with compositional changes in vascular plant and lichen communities, and in particular with the encroachment of the evergreen dwarf shrub Empetrum nigrum. In comparison to vascular plants and lichens, the diversity of bryophytes generally remained more stable over time. Our findings suggest that Fennoscandian heathland and tundra vegetation is transforming towards a more homogenous evergreen dwarf shrub dominated system, which may threaten ecosystem multifunctionality. Our results highlight the importance of exploring biodiversity among different metrics and growth forms to understand the overall changes in heathland and tundra biodiversity.

ecology↗

bioRxiv2024

Forbs in Viking lands: The effect of disturbing dominant graminoids on forb recruitment in tundra grasslands.

Certain graminoids can be successful in grasslands to the extent it is a phenomenon called "the Viking Syndrome". Nevertheless, forbs also make up a substantial part of vascular plant diversity in grasslands and are important resources of mammalian herbivores. Here we assess the hypothesis that forb recruitment is constrained by dominant graminoids, limiting access to safe sites for germination. We report on a disturbance experiment of plots with four different graminoid species in tundra grasslands of the Varanger Peninsula, Norway. Plots were selected to sample both rodent-disturbed and undisturbed areas. The dominant graminoids in each plot were removed, reducing their shading capabilities and belowground rhizome and root systems. Results show that forb recruitment one year following disturbance was significantly enhanced by manual graminoid removal. Dominant graminoid type, small rodent disturbance, initial forb abundance, and abiotic conditions had no effect on forb recruitment, whereas initial species richness had a positive relationship. Furthermore we found that manual disturbance had low impact on the species exchange ratio based on richness (SERr), suggesting that disturbance did not reduce the capacity of species to reside and move within the grassland. Our findings support the hypothesis that forb recruitment is limited by dominant graminoids.

plant biology↗

bioRxiv2023

One does not simply grow well: Performance of grassland plants in home and foreign soil and climate

O_LIPlant-soil feedbacks (PSF) play a substantial role in determining plant performance in native and foreign habitats. Yet, PSF strength may be altered by climatic parameters, creating synergies. Here, we assess performance of alpine grassland species in their native and in foreign soils in an experiment including different climates. C_LIO_LIUsing soil and seeds sampled from six alpine grassland sites spreading in a gradient from Northern Africa to Northern Europe, we compared plant performance in home soil and in five foreign soils, as well as home and foreign climates (simulated temperature and photoperiod in growth chambers). C_LIO_LIWe found that despite a high variability in plant performance between sites, plants generally performed better in their home soil and home climate, than in foreign soil or in foreign climate. However, an interaction between soil and climate effect caused this better performance in home soil to occur only when in foreign climate. Similarly, performance improved in home climate only when plants were also placed in foreign soil. C_LIO_LISynthesis: In contrast to predictions from the literature, no benefit from growing in foreign soils are indicated. At least on the short term, climate change alone is not suggested to affect native grassland plant performance. However, when introduced to a habitat with a similar climate to their native habitat, plants may perform as well as in their native range, but when introduced both to a new soil and climate, plants will do poorly. This finding sheds light on the interactive effect of climate and soil origin, as well as the possible success of plant introductions under a changing climate. C_LI

ecology↗

bioRxiv2023

Long-term herbivore removal experiments reveal different impacts of geese and reindeer on vegetation and ecosystem CO2-fluxes in high-Arctic tundra

O_LIGiven the current and anticipated rates of global change, with associated shifts in herbivore population densities, understanding the role of different herbivores in shaping ecosystem structure and processes is critical for predicting ecosystem responses. Here, we examined the controls exerted by migratory geese and resident, non-migratory ungulates, two dominating yet functionally contrasting herbivores, on the rapidly warming Arctic tundra. C_LIO_LIWe collected vegetation and ecosystem carbon flux data at peak plant growing season in the two longest running herbivore removal experiments in high-Arctic Svalbard. Herbivore exclosures had been set up independently in a wet habitat utilised by barnacle geese (Branta leucopsis) in summer and in mesic-to-dry habitats utilised by wild reindeer (Rangifer tarandus platyrhynchus) year-round. C_LIO_LIExcluding geese produced vegetation state transitions from heavily grazed, moss-dominated (4 g m-2 dry weight of live aboveground vascular plants) to ungrazed, graminoid-dominated (60 g m-2; after 4-yr exclusion) and then horsetail-dominated (150 g m-2; after 15-yr exclusion) tundra. This caused large increases in vegetation carbon and nitrogen pools, dead biomass and moss-layer depth. Modifications in nitrogen concentrations and carbon-to-nitrogen ratios of vegetation and soil suggested overall slower nutrient cycling rates in the short-term absence of geese. Long-term goose removal quadrupled the net ecosystem carbon sequestration by increasing gross ecosystem photosynthesis more than ecosystem respiration. C_LIO_LIExcluding reindeer for 21 years also produced detectable, but weaker, increases in live and dead biomass, vegetation carbon and nitrogen pools, moss-layer depth and ecosystem respiration. Yet, reindeer removal did not alter the chemistry of either vegetation or soil, nor net ecosystem carbon sequestration. C_LIO_LIOur findings suggest that, though both herbivores were key drivers of ecosystem structure and processes, localised effects of geese, highly concentrated in space and time, are larger than those exerted by more widely dispersed reindeer. We illustrate that the impacts of herbivory across the tundra landscape are contingent on the habitat utilised for foraging, its sensitivity, the exerted grazing pressure, and herbivore characteristics. Our results underscore the conspicuous heterogeneity in how Arctic herbivores control ecosystem functioning, with important implications under current and future global change. C_LI

ecology↗

bioRxiv2022

Novel frontier in wildlife monitoring: identification of small rodent species from faecal pellets using Near-Infrared Reflectance Spectroscopy (NIRS)

Small rodents are prevalent and functionally important across worlds biomes, making their monitoring salient for ecosystem management, conservation, forestry and agriculture. Yet, there is a dearth of cost-effective and non-invasive methods for large-scale, intensive sampling. As one such method, fecal pellet counts readily provide relative abundance indices. Given available analytical methods, feces could also allow for determination of multiple ecological and physiological variables, including community composition. We developed calibration models for rodent taxonomic determination using fecal near-infrared reflectance spectroscopy (fNIRS). Our results demonstrate fNIRS as an accurate and robust method for predicting genus and species identity of five co-existing subarctic microtine rodent species. We show that sample exposure to weathering did not reduce accuracy, indicating suitability of the method for samples collected from the field. Diet was not a major determinant of species prediction accuracy in our samples, as diet exhibited large variation and overlap between species. While regional calibration models predicted poorly samples from another region, calibration models including samples from two regions provided a good prediction accuracy for both regions. We propose fNIRS as a fast and cost-efficient high-throughoutput method for rodent taxonomic determination, and highlight its potential for cross-regional calibrations and use on field-collected samples. FNIRS can facilitate rodent population censuses at larger spatial extent than before deemed feasible, if combined with pellet-count based abundance indices. Given the versatility of fNIRS analytics, developing such monitoring schemes can support ecosystem- and interaction-based approaches to monitoring.

ecology↗

bioRxiv2022

Arctic evergreening - encroaching allelopathy in a management blind spot

O_LIOngoing Arctic greening can increase productivity and reindeer pasture quality in the tundra. However, greening may also entail proliferation of unpalatable species, with distinct consequences for pastoral socio-ecological systems (SES). C_LIO_LIWe show extensive greening across 20 reindeer districts in northern Norway between 2003 and 2020. The allelopathic, evergreen dwarf-shrub crowberry biomass increased by 60%, contrasted by smaller increases of deciduous dwarf-shrubs and stagnating forb and graminoid biomass. C_LIO_LIWe found evidence, although uncertain, of a negative relationship between biomass and reindeer densities, but only among forbs, the least abundant plant group. C_LIO_LIOur results challenge the management decision-making, which aims at sustainable pasture management, but which assumes stationary density-dependent relationships. Changes in temporal vs. spatial relationships should be included as management criteria, to avoid mismanaging a SES in transition. C_LIO_LILarge-scale shift towards increased allelopathy may undermine the resource base of a key Arctic herbivore and pastoral SES. C_LI

ecology↗

bioRxiv2020

Holocene plant diversity revealed by ancient DNA from 10 lakes in northern Fennoscandia

The effects of climate change on species richness is debated but can be informed by the past. Here, we assess the impact of Holocene climate changes and nutrients on terrestrial plant richness across multiple sites from northern Fennoscandia using new sedimentary ancient DNA (sedaDNA) data quality control methods. We find that richness increased steeply during the rapidly warming Early Holocene. In contrast to findings from most pollen studies, we show that richness continued to increase through the Middle to Late Holocene even though temperature decreased, with the regional species pool only stabilizing during the last two millennia. Furthermore, overall increase in richness was greater in catchments with higher soil nutrient availability. We suggest that richness will rapidly increase with ongoing warming, especially at localities with high nutrient availability and even in the absence of increased human activity in the region, although delays of millennia may be expected.

ecology↗

bioRxiv2020

One leaf for all: Chemical traits of single leaves measured at the leaf surface using Near infrared-reflectance spectroscopy (NIRS)

O_LIThe leaf is an essential unit for measures of plant ecological traits. Yet, measures of plant chemical traits are often achieved by merging several leaves, masking potential foliar variation within and among plant individuals. This is also the case with cost-effective measures derived using Near-infrared reflectance spectroscopy (NIRS). The calibration models developed for converting NIRS spectral information to chemical traits are typically based on spectra from merged and milled leaves. In this study we ask if such calibration models can be applied to spectra derived from whole leaves, providing measures of chemical traits of single leaves. C_LIO_LIWe sampled cohorts of single leaves from different biogeographic regions, growth forms, species and phenological stages in order to include variation in leaf and chemical traits. For each cohort we first sampled NIRS-spectra from each whole, single leaf, including leaf sizes down to O 4 mm (the minimum area of our NIRS application). Next, we merged, milled and tableted the leaves and sampled spectra from the cohort as a tablet. We applied arctic-alpine calibration models to all spectra and derived chemical traits. Finally, we evaluated the performance of the models in predicting chemical traits of whole, single leaves by comparing the traits derived at the level of leaves to that of the tablets. C_LIO_LIWe found that the arctic-alpine calibration models can successfully be applied to single, whole leaves for measures of Nitrogen (R2=0.88, RMSE=0.824), Phosphorus (R2=0.65, RMSE=0.081), and Carbon (R2=0.78, RMSE=2.199) content. For Silicon content we found the method acceptable when applied to Silicon-rich growth forms (R2=0.67, RMSE=0.677). We found a considerable variation in chemical trait values among leaves within the cohorts. C_LIO_LIThis time- and cost-efficient NIRS-application provides non-destructive measures of a set of chemical traits in single, whole leaves, including leaves of small sizes. The application can facilitate research into the scales of variability of chemical traits and include intraindividual variation. Potential trade-offs among chemical traits and other traits within the leaf unit can be identified and be related to ecological processes. In sum this NIRS-application can facilitate further ecological understanding of the role of leaf chemical traits. C_LI

ecology↗